Cooperative Joint Localization and Clock Synchronization Based on Gaussian Message Passing in Asynchronous Wireless Networks

摘要

Localization and synchronization are very important in many wirelessapplications such as monitoring and vehicle tracking. Utilizing the same timeof arrival (TOA) measurements for simultaneous localization and synchronizationis challenging. In this paper, we present a factor graph (FG) representation ofthe joint localization and time synchronization problem based on TOAmeasurements, in which the non-line-of-sight measurements are also taken intoconsideration. On this FG, belief propagation (BP) message passing andvariational message passing (VMP) are applied to derive two fully distributedcooperative algorithms with low computational requirements. Due to thenonlinearity in the observation function, it is intractable to compute themessages in closed form and most existing solutions rely on Monte Carlomethods, e.g., particle filtering. We linearize a specific nonlinear term inthe expressions of messages, which enables us to use a Gaussian representationfor all messages. Accordingly, only the mean and variance have to be updatedand transmitted between neighboring nodes, which significantly reduces thecommunication overhead and computational complexity. A message passing schedulescheme is proposed to trade off between estimation performance andcommunication overhead. Simulation results show that the proposed algorithmsperform very close to particle-based methods with much lower complexityespecially in densely connected networks.